At least one person has contracted the flu in New York City, and two others on Long Island also have fallen ill from the bug in the midst of a major shortage of vaccine, the state Health Department said yesterday.

The one in Manhattan and two in Nassau were the only cases reported in the state as of Monday, said Health Department spokesman Robert Kenny, who declined to name the patients.

Those numbers are expected to grow dramatically as the height of the flu season – late fall and winter – approaches.

Peak months are December and January.

Last year, the first confirmed case of influenza in the city was reported Oct. 17.

But unlike last year, there is a huge shortage of flu vaccinations. Only about 60 million doses of the 100 million doses that had been ordered are expected to be available nationally.

State Health Commissioner Dr. Antonia Novello yesterday said that New Yorkers should not panic if they have not gotten a flu shot, and added that she is “almost confident” that there will be enough vaccine for those who need it most.

“We need to try to keep it in perspective,” Novello told a state Senate panel during a hearing.

“Because even if you are a high-risk individual, you do not have to get vaccinated today or tomorrow.

“I am almost confident all people at risk will get vaccinated,” Novello said after her testimony.

Statewide, about 5.7 million New York state residents have been identified as being high-risk, including senior citizens, children between 6 and 23 months, pregnant women, health-care workers and people with respiratory problems.

The flu and related illnesses kill about 36,000 people annually, with most of those victims being elderly.